An example of a dispenser that discharges a liquid includes an inkjet head. The inkjet head may be classified as a thermal bubble inkjet head and a piezoelectric inkjet head.
In the thermal bubble inkjet head, when bubbles are generated in a heater, the bubbles flow back in a direction opposite to a liquid discharge outlet (for example, a nozzle of the inkjet head).
In the piezoelectric inkjet head, the liquid flows back in the direction opposite to the liquid discharge nozzle even in a scheme of pressing a thin film connected with a chamber.
A dispenser that discharges the liquid, i.e., the inkjet head, is provided with a flow restriction device (restrictor or neck) on a flow path connected to a liquid supply unit so as to suppress backflow of the bubbles or backflow of the liquid.
For example, the flow restriction device increases flow resistance in a backflow direction by forming a flow path in a backflow direction of the liquid that has a relatively smaller cross-sectional area than a flow path in a discharge direction of the liquid to thereby suppress the backflow of the liquid.
As such, in the case of adopting the flow restriction device for forming the smaller cross-sectional area of the flow path, the dispenser is restrictedly used depending on the size of minute particles or cells included in a discharged liquid. That is, in the dispenser, the minute particles may block a gap between the liquid supply unit and a pressure chamber.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.